MQTT: support MQTT over WebSocket

[Etran-H]

Feature Request

Use Case:

Proposed Change:

support http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718127
mqtt { port: 1883 ws_port: 9001 }

Who Benefits From The Change(s)?

The web application does not support native TCP connection.
MQTT over WebSockets allows you to receive MQTT data directly into a web browser.

Alternative Approaches

[kozlovic]

Yes, it is in the roadmap. Not sure yet if mqtt{} block will have its own websocket port, or if we are going to do like leafnodes that can connect to the general websocket{} block, since you can limit users type of connections. So it is possible that you would have to connect your mqtt client to something like wss://<nats server host>:<websocket port>/mqtt. Again, not sure yet which direction I'll go.

[kozlovic]

Closed with #2735